44 / 2021-06-29 11:01:46

Study on the machined surface quality in laser-assisted machining of Si3N4 ceramics under different material removal modes

Laser assisted machining, Silicon nitride ceramics, 3D surface topography, Work hardening, Service property

The surface quality directly impacts the component performance. Laser assisted machining (LAM) is effective for machining ceramics with a high hardness and high brittleness. Different material removal modes were obtained by single factor experiment and orthogonal experiment and were inferred by comprehensively analysing the macroscopic and microscopic topography of the chips, tool wear, and machined surface. (1) The three-dimensional (3D) topography of a machined Si₃N₄ surface using LAM under different material removal modes was comprehensively characterised and compared using the standard ISO 25178-2:2012 surface texture parameters. The relationship between the 3D topography parameters and service properties was analysed. In ductile material removal mode, the surfaces are anisotropic and cutting marks are clearly visible. Decreasing the material softening degree increases the value of the height and functions parameters. Decreasing the material softening degree also decreases the value of the hybrid and feature parameters. (2) The work hardening phenomenon and mechanism of LAM Si₃N₄ ceramics was studied. The results show that, work hardening is the result of the combined of heat and cutting deformation during cutting. The work hardening degree decreases with the increase of material softening degree.